Hard coat film and optical laminate

Abstract

This hard coating film comprises a transparent substrate and a hard coating layer formed on the transparent substrate, the hard coating layer containing filler, and a blackness of less than 5.0 × 10⁻⁶ under the following conditions. ‑4 cd / m 2 (Conditions: 180-degree luminance angle and 360 cd / m²) 2 A hard coating is tightly deposited on an organic EL display. White and black areas are displayed on the organic EL display in a checkerboard pattern. A shield is set to cover the surface of the organic EL display except for the black areas. The black brightness of the black areas is measured using a spectroradiometer set at a distance of 60 cm from the organic EL display.

Description

Technical Field

[0001] This invention relates to hard coatings and optical laminates.

[0002] This application claims priority under Japanese Patent Application No. 2023-200677, filed on November 28, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] In displays, surface defects such as scratches or fingerprints reduce visibility. Therefore, from the perspective of suppressing surface defects, hard coatings are often applied to the display surface. With the increasing use of touch panels in various operating devices that incorporate displays, the importance of hard coatings has increased; it is claimed that the overall pencil hardness of the film formed on the display needs to be 3H or higher. As a hard coating, it is known that hard coatings contain fillers dispersed to increase hardness.

[0004] In recent years, the popularity of OLED displays has been steadily increasing. OLEDs utilize the self-illumination of each pixel, thus unlike LCDs which rely on a backlight located behind the liquid crystal pixels to illuminate them, OLEDs do not require a backlight.

[0005] In liquid crystal displays (LCDs), to represent black, the liquid crystal pixels display black, i.e., they block light from the backlight. However, the optical rotation properties of liquid crystal molecules alone are insufficient to block light from the backlight, and sometimes some light leakage occurs, resulting in poor brightness (black brightness) in the black areas. Therefore, for LCDs, methods are known to use polarizers or materials with low delay to eliminate light leakage through phase difference (e.g., Patent Document 1).

[0006] In contrast, it is known that in organic EL displays, black can be represented as long as the individual pixels do not emit their own light, thus achieving good black brightness. In recent years, there has been a demand to further improve the contrast ratio of organic EL displays. To improve contrast ratio, improving black brightness is crucial. It is believed that the key factors for improving black brightness depend on the organic EL display itself and the materials and structure of the films used in it.

[0007] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 2005-301227. Summary of the Invention

[0008] The problem that the invention aims to solve When applying a hard coating with dispersed fillers to an organic EL display, light from the emitting region adjacent to the black region sometimes leaks into the black region, resulting in increased black brightness. Even using polarizers or low-latency materials as disclosed in Patent Document 1 in the organic EL display is not effective in addressing black brightness. Furthermore, a hard coating with dispersed fillers that can achieve black brightness suitable for VESA's DisplayHDR 500 True Black certification remains unknown. Therefore, other methods to improve black brightness are needed when applying a hard coating with dispersed fillers to an organic EL display.

[0009] The present invention is proposed in view of the above circumstances, and its object is to provide a hard coating and optical laminate with high hardness and good black brightness when applied to organic EL displays.

[0010] Methods for solving problems To address the aforementioned issues, the present invention provides the following means.

[0011] (1) One aspect of the present invention involves a hard coating film comprising a transparent substrate and a hard coating layer formed on the transparent substrate. The hard coating contains filler. The blackness measured under the following conditions is less than 5.0 × 10⁻⁶. -4 cd / m 2 , (Conditions: 180-degree luminance angle and 360 cd / m²) 2 A hard coating film is tightly applied to an organic EL display. White and black areas are displayed on the organic EL display in a checkerboard pattern. A shield is provided to cover the surface of the organic EL display except for the black areas. The black brightness of the black areas is measured using a spectroradiometer placed 60 cm away from the organic EL display.

[0012] (2) In the hard coating film of (1) above, the hard coating layer contains an acrylic resin, the particle size of the filler is 20 nm or more and 50 nm or less, and the surface of the filler may be modified with (meth)acryloyl groups.

[0013] (3) In the hard coating film of (1) or (2) above, the hard coating layer has: a first layer isolated from the transparent substrate and containing the filler; and a second layer disposed between the transparent substrate and the first layer, wherein the second layer may contain the resin component of the transparent substrate and the resin component of the first layer.

[0014] (4) In the hard coating film of (3) above, the average particle size of the filler is 20 nm or more and 50 nm or less, and the concentration of the filler in the first layer can be 25% or more and 65% or less.

[0015] (5) In the hard coating film of (1) or (2) above, the average particle size of the filler is 20 nm or more and 50 nm or less, and the concentration of the filler in the hard coating film can be 40% or more and 65% or less.

[0016] (6) An optical laminate according to one aspect of the present invention comprises: a hard coating film of any one of (1) to (5) above; and an optical functional layer formed on the hard coating film, wherein the optical functional layer is a layer composed of inorganic oxides or inorganic nitrides.

[0017] (7) In the optical laminate of (6) above, the optical functional layer can be a single film composed of SiO2.

[0018] (8) The optical laminate of (6) or (7) above further comprises an adhesive layer, which is formed between the hard coating layer and the optical functional layer and is in contact with the hard coating layer and the optical functional layer; in the optical functional layer, high refractive index material layers and low refractive index layers are alternately stacked, and the adhesive layer can be in contact with the high refractive index material layers.

[0019] Invention Effects According to the present invention, a hard coating film and an optical laminate with high hardness and good black brightness when applied to organic EL displays can be provided. Attached Figure Description

[0020] [ Figure 1 [Illustration 1] is a cross-sectional view of a hard coating film according to one embodiment of the present invention.

[0021] [ Figure 2 [Image] is a diagram illustrating interface reflection when a hard coating is applied to an organic EL display.

[0022] [ Figure 3 [Image] is a diagram illustrating interface reflection when a hard coating is applied to an organic EL display.

[0023] [ Figure 4 [Image] is a diagram illustrating the scattering when a hard coating containing fillers is applied to an organic EL display.

[0024] [ Figure 5 [Image] is a diagram illustrating the scattering when a hard coating containing fillers is applied to an organic EL display.

[0025] [ Figure 6 [Image] is a diagram illustrating the scattering when a hard coating containing fillers is applied to an organic EL display.

[0026] [ Figure 7 ] is Figure 1 The figure illustrates the black brightness measured when the hard coating is applied to an organic EL display.

[0027] [ Figure 8 [This is a graph showing the correlation between brightness and interparticle distance of a hard coating film 100A containing fillers with particle sizes of 22nm, 42nm, and 80nm when light is incident from the side along the in-plane direction.]

[0028] [ Figure 9 ] is the display Figure 1 A cross-sectional view of a deformed example of a hard coating.

[0029] [ Figure 10 ] Figure 10 (a) is a Figure 1 The graph illustrates the black brightness measured when the hard coating is applied to an organic EL display. Figure 10 (b) is for Figure 9 The figure illustrates the black brightness measured when the hard coating is applied to an organic EL display.

[0030] [ Figure 11 The graph shows the correlation between brightness and interparticle distance of hard coating films 100A and 100B containing fillers with a particle size of 42 nm when light is incident from the side along the in-plane direction.

[0031] [ Figure 12 The graph shows the correlation between brightness and interparticle distance of hard coating films 100A and 100B containing fillers with a particle size of 22 nm when light is incident from the side along the in-plane direction.

[0032] [ Figure 13 [Illustration 1] is a cross-sectional view of an optical laminate according to an embodiment of the present invention.

[0033] [ Figure 14 ]yes Figure 13 A cross-sectional view of the optical laminate involved in the modified example.

[0034] [ Figure 15 ]yes Figure 13 Cross-sectional views of optical laminates involved in other variations.

[0035] [ Figure 16 [This is the measurement pattern displayed on the organic EL when measuring black brightness in the examples and comparative examples.]

[0036] [ Figure 17 [This is a graph showing the results of filler concentration and brightness for Examples 5 to 7 and Comparative Example 4.] Detailed Implementation

[0037] Hereinafter, this embodiment will be described in detail with appropriate reference to the accompanying drawings.

[0038] In the accompanying drawings used in the following description, the featured parts are sometimes enlarged for convenience in order to facilitate understanding of the features of the invention, and the dimensions and proportions of the constituent elements may sometimes differ from the actual figures. The materials, dimensions, etc., exemplified in the following description are merely examples, and the invention is not limited thereto. Appropriate modifications may be made to achieve the desired effect.

[0039] [Hard coating] Figure 1 This is a cross-sectional view of a hard coating film according to one embodiment of the present invention. Figure 1 The hard coating 100A shown comprises a transparent substrate 1 and a hard coating layer 2 formed on the transparent substrate 1. The hard coating layer 2 contains filler 21. The blackness of the hard coating 100A is less than 5.0 × 10⁻⁶ under the following conditions. −4 cd / m 2 .

[0040] (Measurement conditions for black brightness: emission angle 180 degrees, brightness 360 cd / m) 2 A hard coating was applied to an organic EL display, and the black brightness was measured using a spectroradiometer positioned 60 cm away from the organic EL display. The conditions for measuring blackness are detailed below.

[0041] The hard coating 100A is, for example, composed of a transparent substrate 1 and a hard coating layer 2 formed in contact with the transparent substrate 1.

[0042] (Transparent substrate) The transparent substrate 1 can be formed of any transparent material that can transmit light in the visible light region. For example, a plastic film is suitable as the transparent substrate 1. Specific examples of materials constituting the plastic film include: polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins.

[0043] It should be noted that the term "transparent material" in this invention refers to a material with a light transmittance of 80% or more within the wavelength range used, without compromising the effectiveness of this invention.

[0044] In addition, in this embodiment, "(meth)acrylic acid" refers to methacrylic acid and acrylic acid.

[0045] Without significantly impairing optical properties, the transparent substrate 1 may contain a reinforcing material. Reinforcing materials may include, for example, cellulose nanofibers or nano-silica. In particular, polyester resins, acetate resins, polycarbonate resins, and polyolefin resins are suitable as reinforcing materials. Specifically, cellulose triacetate (TAC) substrates are suitable as reinforcing materials.

[0046] Alternatively, a glass film, which is an inorganic substrate, can also be used in the transparent substrate 1.

[0047] The transparent substrate 1 can be a film endowed with optical and / or physical functions. Examples of films with optical and / or physical functions include: polarizers, phase difference compensation films, thermal radiation shielding films, transparent conductive films, brightness-enhancing films, and barrier-enhancing films.

[0048] The thickness of the transparent substrate 1 is not particularly limited, but is preferably 25 μm or more. The film thickness of the transparent substrate 1 is more preferably 40 μm or more.

[0049] If the thickness of the transparent substrate 1 is 25 μm or more, the rigidity of the substrate itself can be ensured, and wrinkles are less likely to occur even when stress is applied to the optical laminate 10. Furthermore, if the thickness of the transparent substrate 1 is 25 μm or more, wrinkles are less likely to occur even when the hard coating 2 is continuously formed on the transparent substrate 1, reducing manufacturing concerns, and is therefore preferred. If the thickness of the transparent substrate 1 is 40 μm or more, wrinkles are even less likely to occur, and is therefore preferred.

[0050] When the manufacturing process is carried out using rollers, the thickness of the transparent substrate 1 is preferably 1000 μm or less, more preferably 600 μm or less. If the thickness of the transparent substrate 1 is 1000 μm or less, the optical laminate 10 during manufacturing and the manufactured optical laminate 10 are easier to wind into a roll, allowing for efficient manufacturing of the optical laminate 10. Furthermore, if the thickness of the transparent substrate 1 is 1000 μm or less, further thinning and weight reduction of the optical laminate 10 can be achieved. If the thickness of the transparent substrate 1 is 600 μm or less, the optical laminate 10 can be manufactured more efficiently, while further thinning and weight reduction can be achieved, which is therefore preferable.

[0051] The surface of the transparent substrate 1 may be pre-treated with etching processes such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, formation, oxidation, and / or primer treatment. By performing these pre-treatments, the adhesion to the hard coating 2 formed on the transparent substrate 1 can be improved. In addition, before forming the hard coating 2 on the transparent substrate 1, it is preferable to perform solvent washing, ultrasonic washing, or other methods on the surface of the transparent substrate 1 as needed, thereby pre-cleaning and removing dust from the surface of the transparent substrate 1.

[0052] (Hard coating) The hard coating 2 must contain adhesive resin 22 and filler 21, and may also contain other components such as dispersants as optional components. The adhesive resin 22 may be a known substance. The filler 21 is contained in the adhesive resin to a extent that does not impair transparency.

[0053] As filler 21, fillers composed of organic materials, inorganic materials, or a combination of both can be used. From the viewpoint of hardness or flexural strength, fillers composed of inorganic materials are preferred, and silica particles composed of silica are even more preferred. Furthermore, from the viewpoint of suppressing the aggregation of filler 21 and thus suppressing the local increase in scattered light caused by filler 21, surface-modified silica particles have good dispersibility in the adhesive resin and are therefore particularly preferred.

[0054] As the adhesive resin used for the hard coating 2, a transparent adhesive resin is preferred, such as a resin that is cured by ultraviolet light or electron beams, i.e., an ionizing radiation-cured resin, a thermoplastic resin, a thermosetting resin, etc.

[0055] Examples of ionizing radiation-cured resins used as adhesive resins for hard coating 2 include: ethyl methacrylate, ethylhexyl methacrylate, styrene, methylstyrene, N-vinylpyrrolidone, etc.

[0056] In addition, examples of compounds that are ionizing radiation-cured resins having two or more unsaturated bonds include: trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, di(trimethylolpropane)tetra(meth)acrylate, di... Multifunctional compounds such as pentaerythritol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanurate tri(meth)acrylate, isocyanurate di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerol tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and di(trimethylolpropane)tetra(meth)acrylate are suitable. Among them, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and pentaerythritol tetraacrylate (PETTA) are particularly suitable. It should be noted that "(meth)acrylate" refers to both methacrylates and acrylates. In addition, as ionizing radiation-cured resins, compounds modified with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone), etc., can also be used. Furthermore, from the viewpoint of film formation or viscoelasticity adjustment of hard coatings, urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, etc., can also be used.

[0057] Examples of thermoplastic resins used as adhesive resins for the hard coating 2 include: styrene-based resins, acrylic resins, (meth)acrylic resins, vinyl acetate resins, vinyl ether resins, halogen-containing resins, alicyclic olefin resins, polycarbonate resins, polyester resins, polyamide resins, cellulose derivatives, silicone resins, and rubbers or elastomers. These thermoplastic resins are preferably non-crystalline and soluble in organic solvents (especially general solvents capable of dissolving various polymers and curing compounds). Particularly from the viewpoint of transparency and weather resistance, styrene-based resins, acrylic resins, (meth)acrylic resins, alicyclic olefin resins, polyester resins, and cellulose derivatives (cellulose esters, etc.) are preferred.

[0058] The hard coating 2 comprises, for example, an adhesive resin 22 and silica particles as filler 21. As described above, the silica particles preferably contain silica particles that have undergone prior surface modification. Surface modification is preferably performed using a silane compound having functional groups. The surface of filler 21 is preferably modified with (meth)acryloyl groups.

[0059] Specific examples of silane compounds include: vinyl-containing silane compounds, (meth)acryloyl-containing silane compounds, amino-containing silane compounds, isocyanate-containing silane compounds, isocyanurate-containing silane compounds, epoxy-containing silane compounds, mercapto-containing silane compounds, etc. One or more of these may be used. The silane compound is appropriately selected according to the type of adhesive resin, but when the adhesive resin contains functional groups, a silane compound having the same functional groups as the adhesive resin is preferred. For example, when the adhesive resin contains a (meth)acrylate compound as an ionizing radiation curable resin, an alkoxysilane compound containing a (meth)acryloyl group is preferred. It should be noted that "(meth)acrylate" refers to methacrylate and / or acrylate. From the perspective of good bonding with the hydroxyl groups present on the surface of silica particles, the silane compound used for surface modification preferably has an alkoxysilyl or silanol group at the end.

[0060] The dispersion of silica particles in the adhesive resin 22 is improved by pre-modifying the surface, or by reacting the surface treatment agent used for surface modification with the adhesive resin, thereby increasing the hardness.

[0061] The average particle size of filler 21 is, for example, 10 nm or more and 100 nm or less, preferably 20 nm or more and 50 nm or less, although it also depends on its concentration in the hard coating 2, but is more preferably 20 nm or more and 30 nm or less. In addition, from the viewpoint of suppressing appearance unevenness in optical applications, the average particle size of filler 21 is preferably 50 nm or less.

[0062] By ensuring that the average particle size of the filler 21 in the hard coating 2 is within the aforementioned range, the haze value reaches at least 2%. With a haze value of 2% or less, the hard coating film 100A has high transparency, becoming a transparent hard coating film. Furthermore, considering the appearance and optical characteristics of the display, a haze value of 1% or less is preferred, and this haze value can also be achieved by ensuring the average particle size of the filler 21 is within the aforementioned range. Specifically, because the haze value is low, contrast is suppressed.

[0063] The concentration of filler 21 in the hard coating 2 is, for example, greater than 0% and less than 80%. Details are described later. The black gloss depends on the area in which filler 21 is present in the hard coating film 100A, i.e., the concentration (interparticle distance) of filler 21 in the hard coating 2 and the particle size of filler 21.

[0064] When the average particle size of the filler 21 in the hard coating 2 is 30 nm or more and 50 nm or less, the concentration of the filler 21 in the hard coating 2 is preferably 23% or more and 50% or less, or more than 0% and less than 12%, more preferably 30% or more and 45% or less. Furthermore, when the average particle size of the filler 21 in the hard coating 2 is 10 nm or more and less than 30 nm, its concentration is preferably more than 0% and less than 30%. However, from the viewpoint of improving the surface hardness of the hard coating and the optical laminate described later, a higher concentration is preferable.

[0065] As fillers contained in the hard coating 2, various reinforcing materials can be used within a range that does not impair optical properties in order to impart toughness to the hard coating 2. Examples of reinforcing materials include cellulose nanofibers.

[0066] The thickness of the hard coating 2 is preferably 0.5 μm or more, more preferably 1 μm or more. The thickness of the hard coating 2 is preferably 100 μm or less, more preferably 30 μm or less. When the thickness of the hard coating 2 is 0.5 μm or more, sufficient hardness can be obtained, thus reducing the likelihood of scratches during manufacturing. Furthermore, when the thickness of the hard coating 2 is 100 μm or less, it results in a thinner and lighter hard coating film 100A. Additionally, when the thickness of the hard coating 2 is 100 μm or less, microcracks in the hard coating 2 that occur when the hard coating film 100A is bent during manufacturing are less likely to form, resulting in good production capacity.

[0067] The hard coating 2 can be a single layer or composed of multiple layers. Furthermore, when the hard coating 2 is composed of multiple layers, the filler can be dispersed in each layer or contained only in the layer furthest from the transparent substrate 1. Additionally, the hard coating 2 can be further endowed with known functions such as ultraviolet absorption, antistatic properties, refractive index adjustment, and hardness adjustment.

[0068] Furthermore, the functions imparted to the hard coating 2 can be applied to a single hard coating or applied to multiple layers in a segmented manner.

[0069] The hard coating 100A according to the above embodiment exhibits a high hardness exceeding 3H (pencil hardness) and good black brightness when applied to an organic EL display. That is, in an organic EL display, the increase in black brightness caused by light leakage from each self-emissive pixel due to interface reflection or scattering in the area where non-self-emissive pixels are located (black area) adjacent to the area where self-emissive pixels are located can be suppressed.

[0070] The following, with appropriate reference to the accompanying drawings, will be discussed... Figure 1 The function of the hard coating shown will be explained. Figure 2 and Figure 3 This diagram illustrates interface reflection when a hard coating is applied to an organic EL display. Figure 2 and Figure 3 As an example, the following situation is shown: Figure 1 The hard coating 100A shown is formed on an organic EL display (OLED). A shielding plate 30 with an opening is formed on the hard coating 100A, and the brightness (black brightness) of the black area of ​​the OLED is measured through the opening using a spectroradiometer 40; however, filler 21 is omitted to simplify the explanation of interface reflection. Additionally, in Figure 2 and Figure 3 For ease of explanation, the hard coating 100A is shown separately from the organic EL display OLED and the masking plate 30, but the hard coating 100A is in contact with the organic EL display OLED and the masking plate 30. Hereinafter, consider the following situation: in the out-of-plane direction (perpendicular to the plane) of the organic EL display OLED, the distance between the spectroradiometer 40 and the organic EL display OLED is 60 cm (measurement angle 2°), and in the in-plane direction of the organic EL display OLED, the distance between the white area W and the spectroradiometer 40 is 50 mm.

[0071] like Figure 2 As shown, in an organic EL display (OLED), each pixel is divided into self-emissive and non-emissive regions. When a white region W and a black region B are displayed in a checkerboard pattern, the light L emitted from the white region W undergoes multiple interface reflections within the hard coating 100A. Each interface reflection results in a loss of photon energy, and the energy of the light detected by the spectroradiometer 40 becomes a smaller value.

[0072] like Figure 3 As shown, of the light L emitted from the white region W, a portion passes directly through the hard coating 100A as transmitted light, while the other portion undergoes interface reflection to become internal reflected light. Figure 2 Compared to the example shown, only a small amount of light undergoes interface reflection and passes through the opening of the shield 30. However, due to its large angle, this light passing through the opening of the shield 30 will not be detected as a signal by the spectroradiometer 40. Figure 2 and Figure 3 In this context, the distance between the white region W and the spectroradiometer 40 in the in-plane direction of the OLED display is larger than the distance between the OLED and the spectroradiometer 40 in the out-of-plane direction. Therefore, it is assumed that light emitted from the white region W and reflected through the interface has a smaller impact on the black region B. It should also be noted that... Figure 2 , Figure 3 This diagram illustrates the effect of interfacial reflection in hard coatings without considering the influence of fillers. In actual hard coating 100A, the following occurs: Figure 2 , Figure 3 Different phenomena, refer to Figure 7 The detailed descriptions of the following diagrams will be provided later.

[0073] Next, using Figures 4-6 The effect of scattering caused by fillers in the case of hard coating films is explained. Figures 4-6 This diagram illustrates the scattering when a hard coating containing fillers is applied to an organic EL display. Figures 4-6 As an example, the following situation is shown: Figure 1 The hard coating 100A shown is formed on an organic EL display (OLED), and a shielding plate 30 is formed on the hard coating 100A. The brightness (black brightness) of the black area of ​​the organic EL display (OLED) is measured using a spectroradiometer 40; however, to simplify the explanation of scattering caused by filler 21, only one filler 21 is shown, and the scattering caused by this filler 21 is explained. Figure 4 The diagram shows the packing material located directly above the white area W; Figure 5 and Figure 6 The diagram illustrates the filler located directly below the opening of the masking plate 30 and directly above the black area B. The fillers shown are for illustrative purposes only and are not intended to show the effect of the filler at that location on the black gloss; the hard coating film 100A contains multiple fillers, not one.

[0074] like Figure 4 As shown, when filler 21 is located above the white region W, light L emitted from the white region W is scattered upon reaching filler 21. When the particle size of filler 21 is below 50 nm, Rayleigh scattering of visible light occurs. Figure 4 The image shows the scattered light spreading in concentric circles. Due to the positional relationship between the opening of the shielding plate 30 and the spectroradiometer 40, the light scattered above the white area W will not be detected by the spectroradiometer 40 as a signal.

[0075] Here, the scattered light I from a single particle via Rayleigh scattering can be calculated using equation (1). As can be seen from equation (1), the scattered light I from Rayleigh scattering largely depends on the particle size. For example, when the refractive index is 1.5, the wavelength is 780 nm, and the particle size is 42 nm, the scattered light I from a single particle is 1.3 × 10⁻⁶ times the incident light I₀. -7 The incident light is multiplied by a factor of two, and most of it does not become scattered light, but travels in a straight line (becoming transmitted light).

[0076] [Mathematical Expression 1] (In Equation (1), I0: incident light, R: interparticle distance, λ: wavelength, n: spatial refractive index, d: particle size) like Figure 5 As shown, when the filler 21 is located directly below the spectroradiometer 40, if the light L emitted from the white region W at a certain angle directly reaches the filler 21, it will be detected by the spectroradiometer 40 as a signal through the opening. That is, it can be said that the scattered light caused by the filler 21 will increase the brightness of the black region, thereby increasing the brightness of the black area.

[0077] like Figure 6 As shown, considering that the filler 21 is located directly below the spectroradiometer 40, from the white area W at a speed of less than Figure 5 The light L emitted at the angle shown in the example. Light L undergoes interface reflection in the hard coating 100A. Furthermore, according to... Figure 3 Following the same principle, each interface reflection results in a loss of photon energy, but if the light reaches the filler 21, it will be scattered. The scattered light is detected as a signal by the spectroradiometer 40. That is, the scattered light caused by the filler 21 will increase the brightness of the black region B, thereby increasing the black brightness.

[0078] Such as using Figures 2-6 As explained, if we consider a single filler, the black brightness reaches a high value due to scattering by the filler 21 located directly below the spectroradiometer 40. The larger the particle size of the filler, the stronger the scattered light caused by the filler. However, in the case of a hard coating film like the hard coating film 100A containing multiple fillers, the possibility that the light emitted from the white region W will reach the filler 21 located directly below the spectroradiometer 40 without being affected by other fillers 21 is infinitely low. Therefore, it is necessary to consider the influence caused by multiple fillers 21. That is, it is necessary to consider (1+cos θ) in the Rayleigh scattering formula (Equation (1)). 2 θ) / 2R 2 The value of .

[0079] Figure 7 Yes Figure 1 The figure illustrates the black brightness measured when the hard coating is applied to an organic EL display. The spectroradiometer 40 detects the scattered light caused by the filler 21 in the measurement region Ra directly below the hard coating 2 as a signal, but does not directly detect the scattered light caused by the filler 21 in the middle region Rb in the in-plane direction of the measurement region Ra as a signal.

[0080] On the one hand, such as Figure 7As shown, in a hard coating film 100A containing multiple fillers, the scattered light from filler 21 located in the intermediate region Rb reaches and is scattered by filler 21 located in the measurement region Ra, and is thus detected as a signal (scattered brightness signal). Furthermore, the light reaching filler 21 in the intermediate region Rb includes light emitted from the white region W and directly reaching the filler, light reaching the filler via interface reflection, and scattered light from other fillers. Light other than that emitted from the white region W and directly reaching the filler loses photon energy due to scattering or interface reflection. Regarding the loss due to scattering in the intermediate region Rb, i.e., scattering loss, the higher the concentration of filler 21, the greater the scattering loss; furthermore, the larger the particle size of filler 21, the greater the scattering loss.

[0081] Furthermore, on the other hand, as mentioned above, the black brightness is increased by the scattered light caused by the filler 21 within the measurement region Ra. Regarding the scattered light from the filler 21 within the measurement region Ra that affects the black brightness, the larger the particle size of the filler 21, the stronger the scattered light; and the higher the concentration of the filler 21, the stronger the scattered light. Therefore, in order to improve hardness and reduce black brightness, it is found important to optimize the particle size and concentration of the filler 21 in the hard coating 2.

[0082] In summary, the measurement conditions of this invention focus on light leakage from the white region W to the black region B, and evaluate the light by blocking direct light from the white region W. The light reaching the measurement area Ra on the front side of the black region B is reflected and scattered within the hard coating 100A. Organic EL displays (OLEDs) have a wide emission angle (approximately 180°), and light is incident on the hard coating at various angles. Light with small incident angles undergoes multiple interface reflections to reach the front side of the black region, resulting in a very weak signal. Light with large incident angles is primarily transmitted to the measurement area Ra on the front side of the black region B through scattering by the filler 21 distributed in the hard coating layer 2.

[0083] The generation of electric dipoles is the primary cause of scattering, and the ease with which this generation occurs is closely related to particle size. Comparatively, particles with sufficiently small wavelengths are suitable for Rayleigh scattering, while larger particles are suitable for Mie scattering. In optical applications, from the viewpoint of avoiding appearance inhomogeneity, a particle size of 50 nm or less is preferred; scattering at this particle size is generally classified as Rayleigh scattering. In this case, the scattered light from a single particle is related to the refractive index of the material and its particle size. Since the refractive index of the binder resin 22 in the hard coating 2 does not change significantly, generally, the larger the particle size of the filler 21, the stronger the scattered light.

[0084] Compared to the incident light, the scattered light from a single filler 21 is extremely weak, with most of the light transmitted unscattered. The light reaching the black region B is closely related to the optical path length and the filler concentration in the region where filler 21 is located. In particular, the filler concentration is related to the probability of scattering and is therefore a factor determining the final scattering intensity. Here, the optical path length refers to the average length of the distance traveled from the white region to the black region within the hard coating. Scattering generated in the optical path becomes a loss, weakening the transmitted light. The transmitted light reaches the front side of the black region (measurement region Ra), where the scattered light becomes the brightness signal, worsening the True Black effect. With a high filler blending concentration, the scattering intensity is strong, the transmitted light is weak, but the scattered brightness signal is enhanced. Therefore, depending on the filler concentration, the brightness of the black region may have extreme values. The relationship between particle size and scattering intensity has been explained, but the relationship with optical path length, for example, explains why light leakage is strong in black regions near the white region and weak in black regions far away.

[0085] In order to investigate the correlation between filler concentration (interparticle distance), filler particle size and black brightness in the hard coating 2, the inventors conducted a simulation.

[0086] Figure 8 This is a graph simulating the correlation between brightness and interparticle distance of a hard coating film 100A containing fillers with particle sizes of 22nm, 42nm, and 80nm when light is incident from the side along the in-plane direction. Figure 8 The graph shown simulates the following brightness: a shield with an opening is formed on a hard coating film, the opening being located approximately 50 nm from the end of the hard coating film along the in-plane direction. The brightness is measured using a spectroradiometer placed 60 cm away from the hard coating film through this opening. Additionally, a brightness of 360 cd / m² is assumed for the incident light. 2 The situation of light.

[0087] Figure 8 In the graph, the horizontal axis represents the average distance between fillers, and the vertical axis represents the estimated brightness of the black area. That is, for example, in the simulation results graph for fillers with a particle size of 22 nm, the result of a filler distance of 22 nm is the result of the fillers in hard coating 2 being in contact with each other. It should also be noted that... Figure 8 Although the simulation results shown take into account Rayleigh scattering caused by fillers, they do not account for scattering caused by the resin contained in the hard coating 2 and scattering caused by the transparent substrate. Therefore, it is assumed that the black brightness measured under various conditions will be more accurate than that measured under actual conditions. Figure 8 The estimated brightness value is higher than the value in the original text. As an increase, when using an 80 μm TAC film as the substrate, the increase is approximately 2.2 × 10⁻⁶. -4 cd / m 2 about.

[0088] like Figure 8 As shown, in a hard coating film containing filler with a particle size of 22 nm, the curve of estimated brightness versus filler distance does not have a maximum value. That is, the larger the filler distance and the lower the concentration of filler 21 in the hard coating layer 2, the lower the estimated brightness value. On the other hand, maximum values ​​were confirmed in hard coating films containing filler with particle sizes of 42 nm and 80 nm. That is, when the filler size is above a certain value, the concentration decreases and the black brightness increases as the filler distance increases to the certain value; as the filler distance increases beyond the certain value, the concentration decreases and the black brightness decreases. It is believed that the maximum value in the simulation results originates from the correlation between the magnitude of scattering loss in the intermediate region Rb and the magnitude of scattered light relative to the light reaching the filler in the measurement region Ra. In addition, it is believed that the filler distance at which the maximum value is obtained depends on the filler particle size, the average length of the light path from the white region W to the black region B in the hard coating film, and the thickness of the layer in which the filler is distributed.

[0089] While it is difficult to precisely demonstrate the relationship between particle concentration and interparticle distance, considering the influence of particle size and filler distance on brightness, in a hard coating 2 containing filler 21 with an average particle size less than 30 nm, it is preferable to set the concentration of filler 21 in the hard coating 2 to achieve an interparticle distance of 25 nm or more. As a simulation result, this concentration in the hard coating 2 is 44.5% or less. In a hard coating 2 containing filler 21 with an average particle size of 30 nm or more and 50 nm or less, the filler concentration in the hard coating 2 is preferably a concentration where the interparticle distance reaches 45 nm to 60 nm, or a concentration where it reaches 280 nm or more. In the former case, the concentration, calculated from simulation values, is 35% or more and 60% or less. Furthermore, the concentration reaching 280 nm or more is 0.3% or less from simulation values. However, the concentration calculated through simulation is the final filler concentration in the hard coating 2, not the concentration during mixing, including solvents.

[0090] Figure 9 yes Figure 1 A cross-sectional view of the hard coating involved in the modified example. Figure 9 In the hard coating film 100B shown, the hard coating layer 2X is isolated from the transparent substrate 1 and has a first layer 2a containing filler 21 and a second layer 2b disposed between the transparent substrate 1 and the first layer 2a. The second layer 2b contains the resin components of the transparent substrate 1 and the resin components of the first layer 2a.

[0091] In the first layer 2a, the filler 21 is dispersed in the adhesive resin 22. The second layer 2b is, for example, a region without filler 21. The boundary between the first layer 2a and the second layer 2b is parallel to the transparent substrate 1 and is the surface where the filler 21 closest to the transparent substrate 1 is located. Specifically, it can be referenced to the end of the filler 21 closest to the transparent substrate 1 on one side of the transparent substrate 1.

[0092] The thickness of the first layer 2a in the hard coating 2X is, for example, 5 μm to 15 μm, accounting for 40% to 80% of the thickness of the hard coating 2X. When the average particle size of the filler 21 is 20 nm to 30 nm, the filler concentration in the first layer 2a of the hard coating 2X is, for example, 10% to 80%, preferably 25% to 65%. When the average particle size of the filler 21 is 30 nm to 50 nm, the filler concentration in the first layer of the hard coating 2X is, for example, 10% to 80%, preferably 25% to 65%.

[0093] The hard coating 2X is configured according to the choice of the resin composition used in forming the hard coating and the transparent substrate 1 as follows: it has a first layer 2a containing filler 21 and a second layer 2b disposed between the transparent substrate 1 and the first layer 2a. The second layer 2b contains the same resin composition as the resin composition of the transparent substrate 1 and the resin composition contained in the first layer 2a. The resin contained in the second layer 2b is not particularly limited and can be a resin formed by simply mixing (dissolving) the resin constituting the transparent substrate 1 and the resin contained in the hard coating 2X. In addition, at least one of the resin constituting the transparent substrate 1 and the resin contained in the first layer 2a can undergo chemical changes by heating, light exposure, etc.

[0094] A method for forming the second layer 2b can be exemplified as follows: When forming a hard coating 2X on a transparent substrate 1, a solvent that is also soluble in the transparent substrate 1 is used as the solvent for dissolving / dispersing the resin constituting it. Any one of cellulose triacetate (TAC), polyethylene terephthalate, polycarbonate, and acrylic resin is selected as the transparent substrate 1, and a resin composition containing propylene glycol monomethyl ether acetate (PGMAC), butyl acetate, cyclohexanone (ANON), etc., in the solvent is selected as the resin composition used to form the hard coating. This dissolves the transparent substrate 1, thereby achieving... Figure 9 The hard coating 2X shown has a second layer 2b between the first layer 2a and the transparent substrate 1. In the formation of... Figure 1 In the case where the hard coating 2 shown contains adhesive resin 22 and filler 21, i.e., constitutes the first layer, the aforementioned materials are not used in the solvent when preparing the hard coating. A resin composition composed of propylene glycol monomethyl ether (PGM) or similar solvent can be used. The solvent is appropriately selected considering the type of transparent substrate 1 used and its solubility.

[0095] If a resin composition containing a solvent that dissolves the transparent substrate 1 is applied as described above and cured by irradiation with ultraviolet (UV) light, a permeation layer (second layer) containing components of the adhesive resin 22 constituting the hard coating 2X and the resin components of the transparent substrate 1 is formed on one side of the transparent substrate during the formation of a hard coating 2X. Due to the dissolution caused by the solvent of the hard coating 2X and the permeation of the resin components, the thickness of the transparent substrate 1 will be slightly reduced.

[0096] By selecting a material for forming the second layer 2b, the composition of the first layer 2a, located in the area containing the filler 21, can be adjusted to achieve the desired optical properties while maintaining the overall thickness of the transparent substrate 1 and the hard coating 2X as desired. The thickness of the first layer 2a and the second layer 2b can be adjusted by the type and amount of the solvent mentioned above. As a result of forming the permeation layer in this way, the adhesion between the transparent substrate 1 and the hard coating 2 becomes good, while the generation of interference fringes caused by the refractive index difference between the layers can be suppressed.

[0097] Figure 10 (a) is a Figure 1 The graph illustrates the black brightness measured when the hard coating is applied to an organic EL display. Figure 10 (b) is for Figure 9 The figure illustrates the black brightness measured when the hard coating is applied to an organic EL display.

[0098] Figure 10 The content of filler 21 in the hard coating layer 2 of the hard coating film 100A shown and Figure 10 The content of filler 21 in the hard coating film 100B shown is the same. On the other hand, the area where filler 21 is located... Figure 10 Compared to the hard coating 2 of the hard coating film 100A shown, in Figure 10 The first layer 2a of the hard coating film 100B shown has a higher filler concentration. Specifically, the filler concentration is increased to {(thickness of hard coating layer 2) / (thickness of first layer 2a)} times. Consequently, the filler concentration in the measurement region Ra, as measured by the spectroradiometer 40, also increases by the same multiple as described above. Therefore, the change in transmitted light in the intermediate region Rb is reduced, and in the hard coating film 100B, the optical properties can be altered without changing the total thickness of the transparent substrate and the hard coating layer.

[0099] Figure 11 This is a graph simulating the correlation between brightness and interparticle distance of a hard coating film 100A and 100B containing filler with an average particle size of 42 nm when light is incident from the side along the in-plane direction. Figure 11 Simulation utilization and Figure 8 The same simulation was performed using a shield with an opening and a spectroradiometer to simulate the brightness of light detected by light incident from the side of the hard coating film through the opening.

[0100] Figure 11 The figure shows the curves for a hard coating film with a uniform structure of 10 μm thickness formed from the same material, and a hard coating film with a first layer of 6 μm thickness and a second layer of 4 μm thickness, depending on their relationship with the transparent substrate. That is, under the same filler spacing, the filler concentration in the first layer of the latter is 1.67 times that in the former hard coating.

[0101] in addition, Figure 12 This is a graph simulating the correlation between brightness and interparticle distance of hard coating films 100A and 100B containing fillers with a particle size of 22 nm, when light is incident from the side along the in-plane direction. Figure 12 In, with Figure 11 Compared to the simulation, only the particle size of the filler is different, while all other conditions are the same.

[0102] Depend on Figure 11 and Figure 12 It was confirmed that even when using fillers with particle sizes in the range of 20–45 nm, the estimated brightness varies depending on whether the hard coating is homogeneous or consists of a first layer containing the filler and a second resin layer formed between the first layer and the transparent substrate. Specifically, a hard coating consisting of both a first and a second layer was found to exhibit a lower estimated brightness compared to a hard coating consisting solely of a first layer. Furthermore, for any filler particle size, the estimated brightness changes with respect to the filler distance in a consistent manner, independent of the presence or absence of a second layer. With a filler particle size of 42 nm, a maximum value was observed at a filler distance of approximately 110 nm.

[0103] According to the hard coating films 100A and 100B involved in the above embodiments, the hard coating layers 2 and 2X contain filler 21, and the concentration and particle size of filler 21 are adjusted, thereby achieving the standard known as True Black, i.e., a black brightness of less than 5.0 × 10⁻⁶, when applied to organic EL displays. -4 cd / m 2 Thus, the hard coatings 100A and 100B described in the above embodiments can achieve excellent black gloss.

[0104] [Optical laminate] Figure 13 This is a cross-sectional view of an optical laminate according to one embodiment of the present invention. Figure 13The optical laminate 200A shown includes the hard coating film 100A described in the above embodiment and an optical functional layer 50A formed on the hard coating layer 2. The optical functional layer 50A is a layer composed of inorganic oxides or inorganic nitrides. Here, "on the hard coating layer 2" is not limited to a configuration in contact with the hard coating layer 2, and may also be formed with other layers in between. The optical laminate 200A further includes, for example, an adhesive layer 3 formed between the hard coating layer 2 and the optical functional layer 50A, and in contact with both the hard coating layer 2 and the optical functional layer 50A; and an antifouling layer 6 formed on the optical functional layer 50A.

[0105] (Sealed layer) The bonding layer 3 is formed to ensure good adhesion between the hard coating layer 2 (an organic film) and the optical functional layer 50A (an inorganic film). The bonding layer 3 is preferably a layer composed of an oxygen-deficient metal oxide or a metal. An oxygen-deficient metal oxide refers to a metal oxide with an insufficient number of oxygen atoms compared to its stoichiometric composition. Examples of oxygen-deficient metal oxides include SiO₂. x AlO x TiO x ZrO x CeO x MgO x ZnO x TaO x SbO x SnO x MnO x Etc. Additionally, metals that can be listed include: Si, Al, Ti, Zr, Ce, Mg, Zn, Ta, Sb, Sn, Mn, In, etc. The sealing layer 3 can, for example, be SiO₂. x Materials with x greater than 0 and less than 2.0. Additionally, the adhesive layer can be formed from a mixture of various metals or metal oxides.

[0106] From the viewpoint of maintaining the adhesion between the hard coating and the optical functional layer and obtaining good optical properties, the thickness of the adhesion layer is preferably greater than 0 nm and less than 20 nm, and particularly preferably greater than 1 nm and less than 10 nm.

[0107] (Optical functional layer) Figure 13The optical functional layer 50A of the optical laminate 200A shown is an anti-reflective laminate. The optical functional layer 50A is composed of inorganic oxides or inorganic nitrides. The optical functional layer 50A is a four-layer laminate consisting of alternating high-refractive-index layers 4 and low-refractive-index layers 5, starting from the sealing layer 3 side. In the optical functional layer 50A, the high-refractive-index layer and low-refractive-index layer closest to the transparent substrate 1 are respectively referred to as the first high-refractive-index layer 4a and the first low-refractive-index layer 5a, and the high-refractive-index layer and low-refractive-index layer furthest from the transparent substrate 1 are respectively referred to as the second high-refractive-index layer 4b and the second low-refractive-index layer 5b. There is no particular limitation on the number of high-refractive-index layers 4 and low-refractive-index layers 5; the number of high-refractive-index layers 4 and low-refractive-index layers 5 can be arbitrary.

[0108] exist Figure 13 In the optical laminate 200A shown, since the optical functional layer 50A is composed of alternating layers of low-refractive-index layer 5 and high-refractive-index layer 4, light incident from the anti-fouling layer 6 side will interfere with each other due to the optical functional layer 50A, thereby reducing the intensity of reflected light and performing an anti-reflection function. Therefore, an anti-reflection function that prevents light incident from the anti-fouling layer 6 side from being reflected in one direction can be obtained.

[0109] The low refractive index layer 5 may contain, for example, a metal oxide. Considering ease of acquisition and cost, the low refractive index layer 5 may contain an oxide of Si, preferably a layer with SiO2 (an oxide of Si) as its main component. The SiO2 monolayer film is colorless and transparent. In this embodiment, the main component of the low refractive index layer 5 refers to a component that accounts for 50% by mass or more in the low refractive index layer 5.

[0110] When the low-refractive-index layer 5 is a layer mainly composed of Si oxide, it may contain less than 50% by mass of other elements. The content of elements other than Si oxide is preferably 10% or less. As other elements, for example, Na may be contained to improve durability; Zr, Al, and N may be contained to improve hardness; and Zr and Al may be contained to improve alkali resistance.

[0111] The refractive index of the low refractive index layer 5 is preferably 1.20 to 1.60, more preferably 1.30 to 1.50. Examples of dielectrics used for the low refractive index layer 5 include magnesium fluoride (MgF2, refractive index 1.38).

[0112] The refractive index of the high refractive index layer 4 is preferably 2.00 to 2.60, more preferably 2.10 to 2.45. Examples of dielectrics used for the high refractive index layer 4 include: niobium pentoxide (Nb₂O₅, refractive index 2.33), titanium oxide (TiO₂, refractive index 2.33 to 2.55), tungsten oxide (WO₃, refractive index 2.2), cerium oxide (CeO₂, refractive index 2.2), tantalum pentoxide (Ta₂O₅, refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium tin oxide (ITO, refractive index 2.06), and zirconium oxide (ZrO₂, refractive index 2.2).

[0113] If it is desired to impart conductive properties to the high refractive index layer 4, ITO or indium zinc oxide (IZO) can be selected, for example.

[0114] For example, the optical functional layer 50A preferably uses a layer made of niobium pentoxide (Nb2O5, refractive index 2.33) as the high refractive index layer 4 and a layer made of SiO2 as the low refractive index layer 5.

[0115] The thickness of the low refractive index layer 5 only needs to be between 1 nm and 200 nm, and the wavelength range required for anti-reflection function can be appropriately selected.

[0116] The thickness of the high refractive index layer 4 can be, for example, above 1 nm and below 200 nm, and can be appropriately selected according to the wavelength range required for anti-reflection function.

[0117] The film thicknesses of the high refractive index layer 4 and the low refractive index layer 5 can be appropriately selected according to the design of the optical functional layer 50A.

[0118] For example, a high refractive index layer 4 of 5-50 nm, a low refractive index layer 5 of 10-80 nm, a high refractive index layer 4 of 20-200 nm, and a low refractive index layer 5 of 50-200 nm can be formed sequentially from the side of the sealing layer 3.

[0119] In the layer forming the optical functional layer 50A, a low refractive index layer 5 is disposed on the side of the anti-fouling layer 6. When the low refractive index layer 5 of the optical functional layer 50A is in contact with the anti-fouling layer 6, the anti-reflective performance of the optical functional layer 50A is good, and therefore preferred.

[0120] (Anti-fouling layer) An anti-fouling layer 6 is formed on the outermost layer of the optical functional layer 50A to prevent contamination of the optical functional layer 50A. In addition, when applied to touch panels and the like, the anti-fouling layer 6 suppresses wear and tear on the optical functional layer 50A through its abrasion resistance.

[0121] In this embodiment, the antifouling layer 6 is composed of a vapor-deposited film obtained by vapor deposition of an antifouling material. In this embodiment, the antifouling layer 6 is formed by vacuum vapor deposition of a fluorine-based organic compound as an antifouling material on one side of the low-refractive-index layer 5 constituting the optical functional layer 50A. In this embodiment, since the antifouling material contains a fluorine-based organic compound, an optical laminate 10 with even better abrasion resistance and alkali resistance can be formed.

[0122] As the fluorinated organic compound constituting the antifouling layer 6, a compound consisting of fluorinated modified organic groups and reactive silyl groups (e.g., alkoxysilanes) is preferred. Examples of commercially available products include: OPTOOL DSX (manufactured by Daikin Industries, Ltd.), KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

[0123] When the fluorinated organic compound constituting the antifouling layer 6 is a compound composed of fluorinated modified organic groups and reactive silyl groups (e.g., alkoxysilanes), and the low refractive index layer 5 of the optical functional layer 50A in contact with the antifouling layer 6 is a layer composed of SiO2, siloxane bonds are formed between the silanol groups that form the backbone of the fluorinated organic compound and the SiO2. Therefore, the optical functional layer 50A and the antifouling layer 6 have good adhesion, which is preferable.

[0124] The optical thickness of the anti-fouling layer 6 only needs to be in the range of 1 nm or more and 20 nm or less, preferably in the range of 3 nm or more and 10 nm or less. If the thickness of the anti-fouling layer 6 is 1 nm or more, sufficient wear resistance can be ensured when the optical laminate 10 is applied to touch panels and the like. In addition, if the thickness of the anti-fouling layer 6 is 3 nm or more, the liquid resistance of the optical laminate 10 is improved. Furthermore, if the thickness of the anti-fouling layer 6 is 20 nm or less, the vapor deposition time can be completed in a short time, allowing for efficient manufacturing.

[0125] Figure 14 yes Figure 13 A cross-sectional view of the optical laminate involved in the modified example. Figure 14 The optical functional layer 50B in the optical laminate 200B shown is different from the optical functional layer 50A in the optical laminate 200A. For example... Figure 14 As shown, the optical laminate 200B may include an optical functional layer 50B, which is a monolayer film of an inorganic oxide or inorganic nitride. From the perspective of ease of acquisition and cost, the optical functional layer 50B may contain an oxide of Si. For example, the optical functional layer 50B is a monolayer film containing SiO2 (an oxide of Si) as its main component. The SiO2 monolayer film is colorless and transparent. In this embodiment, the main component of the optical functional layer 50B refers to a component with a content of 50% by mass or more in the optical functional layer 50B. The optical functional layer 50B may be a layer composed of SiO2.

[0126] Figure 15 yes Figure 13 A cross-sectional view of an optical laminate involved in another variation. Figure 15 In the optical laminate 200C shown, an adhesive layer 3, an optical functional layer 50A, and an anti-fouling layer 6 are provided on the hard coating film 100B. Figure 15 As shown in the optical laminate 200C, the optical laminate involved in this embodiment can be configured such that an optical functional layer is formed on a hard coating film having a first layer 2a and a second layer 2b.

[0127] In the optical laminate according to this embodiment, other layers may be provided on the surface opposite to the side of the transparent substrate 1 where the hard coating layers 2, 2X and the optical functional layers 50A, 50B are formed. Examples include: an adhesive layer attached to the display, a release layer provided on the adhesive layer, etc.

[0128] The adhesive layer is a layer that adheres to the display, etc. Examples of adhesive layers include acrylic adhesives, silicone adhesives, and polyurethane adhesives. The release layer is a layer that protects the adhesive layer and is peeled off at the moment of bonding, allowing the exposed adhesive layer to be attached. Examples of release layers include paper or film coated with a release agent. The adhesive layer may or may not have a separate substrate on the transparent substrate 1 side. That is, the adhesive layer may be formed directly on the transparent substrate 1 or formed in between the substrate; from the viewpoint of facilitating operation of the optical laminate and the display to which the optical laminate is attached, it is preferable to have a substrate layer on the transparent substrate 1 side.

[0129] The optical laminate according to this embodiment, similar to the hard coating film according to the above embodiment, can provide an optical laminate with high hardness and good black brightness when applied to an organic EL display. Example

[0130] The following describes embodiments of the present invention. The present invention is not limited to the following embodiments.

[0131] <Adjustment of the composition for hard coating> To prepare the hard coating films of Examples 1 to 4 and Comparative Examples 1 to 3 below, photocurable resin compositions containing fillers were prepared, excluding Comparative Example 1. The resin compositions are shown in Tables 1 and 2, with fillers, acrylates, leveling agents, and photopolymerization initiators dissolved in solvents and adjusted. Table 1 shows the formulation with the total resin composition including solvent being 100%. Table 2 shows the formulation without solvent. That is, Table 2 shows the formulation with the total solid content being 100%. The % in the tables represents the proportion of the resin composition, expressed as mass%.

[0132] [Table 1] [Table 2] [Example 1-1] First, a cellulose triacetate (TAC) substrate with a thickness of 80 μm was prepared as a transparent substrate. The resin composition of Example 1 shown in Table 1 was coated onto the transparent substrate using a gravure coating machine, resulting in a hard coating thickness of 10 μm before curing. Then, the resin composition coated on the transparent substrate was cured by light irradiation, thereby preparing the product as shown in Table 1. Figure 9 The image shows a hard coating film formed on a transparent substrate, consisting of a second layer containing a resin component of the transparent substrate and a resin component of the hard coating, and a first layer containing fillers.

[0133] It should also be noted that the PGMAC-4130Y (manufactured by Nissan Chemical Co., Ltd.) used as a filler in Examples 1-1 is a filler with an average particle size of 42 nm, formed by modifying the surface of silica particles with (meth)acryloyl groups.

[0134] [Example 2-1] Except for changing the resin composition containing filler to the material shown in Example 2 of Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0135] In Example 2-1, the thickness of the first layer in the hard coating was made thinner than that in Example 1 by changing the solvent of the resin composition.

[0136] [Example 3-1] Except that the resin composition containing filler was changed to the material of Example 3 shown in Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0137] In Example 3-1, by changing the solvent of the resin composition to PGM (propylene glycol monomethyl ether), the following was prepared: Figure 1 The hard coating shown is provided in which a hard coating containing resin and filler is disposed in contact with a transparent substrate.

[0138] PGMAC-3140Y (manufactured by Nissan Chemical Co., Ltd.) used as a filler is a filler with an average particle size of 22 nm, formed by surface modification of silica particles with (meth)acryloyl groups.

[0139] [Example 4-1] Except for changing the resin composition to the material of Example 4 shown in Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0140] In Example 4-1, the thickness of the first and second layers of the hard coating was adjusted by changing the ratio of the resin composition.

[0141] [Comparative Example 1-1] Except that the resin composition was changed to the material of Comparative Example 1 shown in Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0142] In Comparative Example 1-1, a hard coating film with a filler-free hard coating layer formed on a transparent substrate was prepared using a filler-free resin composition.

[0143] [Comparative Example 2-1] Except that the resin composition was changed to the material of Comparative Example 2 shown in Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0144] In Comparative Example 2-1, a hard coating film without a first layer was formed on a transparent substrate by using PGM as a solvent.

[0145] [Comparative Example 3-1] Except that the resin composition was changed to the material of Comparative Example 3 shown in Table 1, a hard coating film was prepared in the same manner as in Example 1.

[0146] In Comparative Example 3-1, the thickness of the first layer was reduced and the thickness of the second layer was increased by changing the ratio, and IPA-ST-L (manufactured by Nissan Chemical) unmodified silica was used as filler.

[0147] Furthermore, as Examples 1-2, 2-2, 3-2, 4-2, and Comparative Examples 1-2, 2-2, and 3-2, an adhesive layer, an optical functional layer, and an antifouling layer were formed on the hard coating layer prepared as Examples 1-1, 2-1, 3-1, 4-1, and Comparative Examples 1-1, 2-1, and 3-1 using the following method, thereby creating an optical laminate (anti-reflective film). Examples 1-1 and 1-2 are sometimes collectively referred to as Example 1. Other examples or comparative examples are also sometimes collectively referred to in the same way.

[0148] <How to manufacture anti-reflective film> The surface of the hard coating was treated with a 5kW glow discharge. Then, using Si and Nb targets as sputtering targets and a mixture of Ar and O2 gases, a bonding layer and an optical functional layer were continuously formed on the hard coating by reactive sputtering.

[0149] That is, the following layers are sequentially formed on the hard coating: a 3nm layer of oxygen-deficient Si oxide (SiO2). x, a sealing layer composed of (0 < x < 2); a first high refractive index material layer composed of Nb2O5 with a thickness of 10 nm; a first low refractive index material layer composed of SiO2 with a thickness of 26 nm; a second high refractive index material layer composed of Nb2O5 with a thickness of 110 nm; and a second low refractive index material layer composed of SiO2 with a thickness of 85 nm.

[0150] Next, under the conditions of a vapor deposition chamber pressure of 0.01 Pa, a vapor deposition temperature of 230 °C, and a holding time of 7.2 seconds, a 3-nm-thick antifouling layer composed of an alkoxysilane compound (KY1903-1, manufactured by Shin-Etsu Chemical Co., Ltd.) having a perfluoropolyether group was formed by vapor deposition on the SiO2 film on the outermost layer of the optical functional layer, thereby fabricating the optical laminate (antireflection film) of the embodiment.

[0151] <Structural Evaluation> The cross-sections of the hard coatings fabricated in the above-described examples and comparative examples were observed using an optical microscope to evaluate the laminated structure. In the observed cross-sections, the distance from the outermost surface of the filler closest to the transparent substrate was measured as the thickness of the second layer.

[0152] <Evaluation of Black Luminance> The fabricated sample was pasted onto the organic EL display (170 mm × 290 mm) of a notebook computer (ASUS ZenBook 13 OLED) equipped with an organic EL display. A prescribed measurement pattern was displayed on the organic EL display. The settings of the organic EL display were as follows: brightness setting: MAX, HDR: enabled, emission angle: 180°, brightness: 360 cd / m 2 . Figure 16 is the measurement pattern displayed on the organic EL during the measurement of black luminance in the examples and comparative examples. As Figure 16 shown, the white area W and the black area B in the measurement pattern are arranged in a checkerboard pattern. A shutter was set on the hard coating so as to cover the area of the organic EL display except for the black area B in which the measurement area Ra is located. The black area B in which the measurement area Ra is located is exposed through an opening provided in the shutter. The black area B in which the measurement area is located has a size of 80 mm × 100 mm, and the measurement area is located at its center of gravity. Measurement was performed at a measurement angle of 2° using a spectroradiometer (TOPCON SR-UL1R) arranged 60 cm away from the organic EL display. These measurement conditions satisfy the measurement standard of VESA's True Black.

[0153] The measurement of black luminance was performed separately for the following cases: when the hard coating was applied to the organic EL display and when the antireflection film was applied to the organic EL display.

[0154] <Pencil Hardness> The pencil hardness of the prepared hard coating (HC film) and antireflective film (AR film) was determined using a method based on JIS K5600-5-4.

[0155] <Haze Value> The haze value of the prepared hard coating film was determined using a method based on JIS-K-7136.

[0156] [Table 3] The overall thickness of the hard coating in Table 3 represents the overall thickness of the hard coating before curing. The values ​​for the thickness of the second layer, the concentration in the first layer, the black gloss, the pencil hardness, and the haze are averages of the three samples prepared. Additionally, the filler concentration in Table 3 refers to the mass percentage of filler in the hard coating.

[0157] Furthermore, in hard coatings such as those in Examples 1 and 2, where the filler particle size is between 30 nm and 50 nm and the filler concentration in the first layer is between 25% and 65%, low black brightness values ​​were observed. Similarly, in hard coatings such as those in Examples 3 and 4, where the filler particle size is below 30 nm and the filler concentration in the first layer or homogeneous hard coating is between 25% and 65%, low black brightness values ​​were also observed. Moreover, in Examples 1 to 4, the pencil hardness is high, satisfying both the hardness requirement and the VESA standard known as True Black. In particular, in Examples 1 to 4, the measured black brightness when using hard coatings was all less than 3.5 × 10⁻⁶. -4 (cd / m 2 (wherein, in Examples 1, 3, and 4, the value is less than 3.0 × 10⁻⁶.) -4 (cd / m 2 In Example 4, the value was less than 2.0 × 10⁻⁶. -4 (cd / m 2 Furthermore, the black brightness when the anti-reflective film was applied was 3.0 × 10⁻⁶ in Examples 1 through 4. -4 (cd / m 2 )the following.

[0158] In contrast, in hard coatings like Comparative Example 1, where the hard coating does not contain fillers, there is no scattering effect caused by fillers, resulting in lower black brightness but lower pencil hardness. Furthermore, in Comparative Example 2, where the filler particle size is 42 nm and the thickness is 10 μm without a second layer, the filler concentration is 31.54%, resulting in insufficient black brightness.

[0159] Furthermore, in Comparative Example 3, which used fillers without (meth)acrylyl surface modification, a significantly higher black brightness was observed compared to Example 2, where all conditions were identical except for whether the filler was surface modified. This is believed to be because the filler surface was not surface modified with (meth)acrylyl, causing the fillers to aggregate, resulting in a larger pseudo-particle size (apparent particle size), and the aggregated particles led to localized enhancement of scattered light.

[0160] [Examples 5-7, Comparative Example 4] According to the formulations shown in Table 4, the hard coating films described in Examples 5-7 and Comparative Example 4 were prepared. The resin composition was coated onto a transparent TAC substrate using a gravure coating machine to achieve a thickness of 10 μm, and then cured by light irradiation to produce films as shown in Table 4. Figure 1 The hard coating shown.

[0161] The filler concentration in the hard coating of Example 5 corresponds to Figure 8 The data in the simulation showed a filler distance of approximately 75 nm.

[0162] The filler concentration in the hard coating of Example 6 corresponds to Figure 8 The data in the simulation is based on a filler distance of 120 nm.

[0163] The filler concentration in the hard coating of Example 7 corresponds to Figure 8 The data in the simulation showed a filler distance of approximately 55 nm.

[0164] The filler concentration in the hard coating of Comparative Example 4 was 0%. Figure 8 In the simulation, the distance between the packings is considered to be infinite.

[0165] [Table 4] (Brightness Evaluation) For Examples 5 to 7 and Comparative Example 4, measurements were performed to determine the similarity to... Figure 8 The graph shows the data corresponding to the simulated conditions. That is, the brightness of the hard coating was measured using the same shield and spectroradiometer used to measure black brightness in the above embodiment. The brightness was measured using a spectroradiometer positioned 60 cm from the hard coating, through an opening in the shield.

[0166] Figure 17 This is a graph showing the results of filler concentration and brightness for Examples 5-7 and Comparative Example 4. (Example) Figure 17As shown, in Examples 5 and 7 with the same filler concentration, Example 7 exhibits lower brightness, while Example 6, with a filler concentration between Example 7 and Comparative Example 4, exhibits higher brightness than Examples 5 and Comparative Example 4, suggesting the existence of a maximum value. Thus, based on Figure 8 The simulation results and Figure 17 The correlation was confirmed in the curve of the measured values, and the correlation was also confirmed. Figure 8 The appropriateness of the simulation results.

[0167] Symbol Explanation 1: Transparent substrate; 2, 2X: Hard coating; 2a: First layer; 2b: Second layer; 3: Sealing layer; 4: High refractive index layer; 4a: First high refractive index layer; 4b: Second highest refractive index layer; 5: Low refractive index layer; 5a: First low-refractive-index layer; 5b: Second low-refractive-index layer; 6: Anti-fouling layer; 10: Optical laminates; 21: Packing material; 22: Resin; 30: Blindfold; 40: Spectroradiometer; 50A, 50B: Optical functional layers; 100A, 100B: Hard coating; 200A: Optical laminate; 200B: Optical laminate; 200C: Optical laminate.

Claims

1. A hard coating film comprising a transparent substrate and a hard coating layer formed on the transparent substrate, The hard coating contains filler. The blackness of the hard coating film measured under the following conditions is less than 5.0 × 10⁻⁶. -4 cd / m 2 , Conditions: 180-degree luminance and 360 cd / m² 2 A hard coating film is tightly applied to an organic EL display. White and black areas are displayed on the organic EL display in a checkerboard pattern. A shield is provided to cover the surface of the organic EL display except for the black areas. The black brightness of the black areas is measured using a spectroradiometer placed 60 cm away from the organic EL display.

2. The hard coating film according to claim 1, wherein, The hard coating contains an acrylic resin. The filler has a particle size of 20 nm or more and 50 nm or less. The surface of the filler is modified with (meth)acryloyl groups.

3. The hard coating film according to claim 1, wherein, The hard coating comprises: a first layer isolated from the transparent substrate and containing the filler; and a second layer disposed between the transparent substrate and the first layer. The second layer comprises the resin components of the transparent substrate and the resin components of the first layer.

4. The hard coating film according to claim 3, wherein, The average particle size of the filler is above 20 nm and below 50 nm. The concentration of the filler in the first layer is above 25% and below 65%.

5. The hard coating film according to claim 1, wherein, The average particle size of the filler is above 20 nm and below 50 nm. The concentration of the filler in the hard coating is above 40% and below 65%.

6. An optical laminate comprising: a hard coating film according to any one of claims 1 to 5; and an optical functional layer formed on the hard coating film. The optical functional layer is a layer composed of inorganic oxides or inorganic nitrides.

7. The optical laminate according to claim 6, wherein, The optical functional layer is a single-layer film composed of SiO2.

8. The optical laminate of claim 6, further comprising an adhesive layer formed between the hard coating layer and the optical functional layer, and in contact with both the hard coating layer and the optical functional layer. In the optical functional layer, high-refractive-index material layers and low-refractive-index layers are stacked alternately. The sealing layer is in contact with the high refractive index material layer.

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